Just like how every sponsor has spies, every sponsor also has trade routes. ARC doesn't scale off number of cities, but neither does Polystralia. If you have 1 city, Polystralia has 66% more trade routes, but does not have the option for the overpowered internal trade routes. If you have 4 or more cities, Polystralia's bonus is less than 20% more trade routes. Meanwhile, ARC still has 25% faster ops and an easier time maintaining intrigue.